Early in the morning, the eggs are checked for signs of fertilization. At this time, normally fertilized eggs will have 2 nuclei in the center, one from the egg and one from the sperm. (as shown below)
Any number of nuclei greater or lesser than 2 indicates abnormal fertilization. Normally fertilized eggs are now considered to be embryos, and are separated from the unfertilized and abnormally fertilized eggs.
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http://216.239.51.104/search?q=cache:hLEqZhOUACUJ:www.gateway.org/content/pdf/pill.pdf+no+such+thing+as+a+%22fertilized+egg%22&hl=en
There is no such thing as a fertilized egg; there is a unique human being who results from the union of sperm and egg. (2) Conception is the same as fertilization, and when it occurs, pregnancy has begun. (Reading: "Emergency Contraception,"http://www.owt.com/ppcw/mornaftr.html)